Question about a proof of a theorem about roots of polynomials in field extensions

Course Queries Syllabus Queries 3 years ago

7.25K 2 0 0 0

User submissions are the sole responsibility of contributors, with TuteeHUB disclaiming liability for accuracy, copyrights, or consequences of use; content is for informational purposes only and not professional advice.

Answers (2)

Post Answer
profilepic.png
manpreet Tuteehub forum best answer Best Answer 3 years ago

 

There is a theorem in my book which says the following:

Let KK be a field and let f(X)K[X]f(X)∈K[X] be irreducible over KK. Then there exists a field extension L/KL/K, such that uL∃u∈Lf(u)=0f(u)=0.

Proof: Notice that KK[X]/(f(x))K⊆K[X]/(f(x)). Clearly, K[X]/(f(x))K[X]/(f(x)) is a field since (f(x))(f(x)) is maximum ideal. If we take u=X¯¯¯¯u=X¯, then f(u)=f(X¯¯

0 views
0 shares

profilepic.png
manpreet 3 years ago

X¯¯¯¯ means the class of XX mod f(X)f(X) in the quotient ring K[X]/(f(x))K[X]/(f(x)).

Now, given gK[X]g∈K[X], consider the associated polynomial function in K[X]/(f(x))K[X]/(f(x)). Then, by the definition of the ring operations in K[X]/(f(x))K[X]/(f(x)), we have g(u)=g(X¯¯¯¯)=g(X)¯¯¯¯¯¯¯¯¯font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; line-height: no


0 views   0 shares

No matter what stage you're at in your education or career, TuteeHUB will help you reach the next level that you're aiming for. Simply,Choose a subject/topic and get started in self-paced practice sessions to improve your knowledge and scores.

Similar Forum